1. Field of the Invention
The invention relates generally to the field of microelectronic fabrication. More particularly, the invention relates to improving the yield and line width performance of liquid polymers.
2. Discussion of the Related Art
Lithography process is one of the major drivers of semiconductor industry in its relentless progress in achieving smaller feature sizes with improved yields. More specifically, improved critical dimension (CD) control and reduced process-induced defect and particle counts need to be satisfied simultaneously.
The develop fluid module process plays a significant role in the patterning of increasingly smaller line widths. Regions of high and low dissolution rates are created on the resist film as a result of the sequence of photolithography process steps preceding the develop process. During a develop process, images transferred to the resists film are developed into three dimensional structures by a wet process. The subsequent etch process (mostly dry) transfers this image onto the substrate (Si, SiO.sub.2, poly Si, etc.).
There are many variations of a good develop process. In general, a typical develop process has two main parts. In the first part, developer fluid is dispensed over a wafer spinning at a low rpm followed by a static puddle formation and a long static or oscillating step at which regions of high dissolution rate are etched away, creating 3-dimensional images on the film. Quality of patterned images, value of side wall angles and CD control, are all strongly affected by the first part of the develop process. The chemical wet etch step is immediately followed by a deionized (DI) water rinse step whose main function is to wash away dissolved resist and developer fluid mixture with minimum particle and defect count on the patterned wafer. Naturally, the rinse step is extremely crucial in improving yield of a lithography process.
Heretofore, the requirements of improved critical dimension control, reduced process-induced defect counts and reduced process-induced particle counts referred to above have not been fully met. What is needed is a solution that simultaneously addresses all of these requirements.